The present invention relates to a positive radiation-sensitive composition for use in the manufacturing process of semiconductors, e.g., a lithographic printing plate and IC, the manufacture of circuit substrates, e.g., a liquid crystal and a thermal head, and other photo fabrication processes.
As the resists for use in the pattern formation of lithography using far ultraviolet rays and eximer laser beams, there are chemical amplification resist compositions disclosed in U.S. Pat. No. 4,491,628 and European Patent 29,139. The chemical amplification photoresist is a pattern-forming material of generating an acid on the exposed area upon irradiation with radiation such as far ultraviolet ray and causing a reaction using the acid generated as a catalyst to change the solubility in a developer of the areas irradiated or not irradiated with the active radiation and thereby form a pattern on the substrate.
The above chemical amplification positive resist compositions can be classified roughly into the following, i.e., a three-component system comprising an alkali-soluble resin, a compound which generates an acid upon radiation exposure (a photo-acid generator), and a dissolution-inhibiting compound which inhibits the dissolution of an alkali-soluble resin and has an acid-decomposable group; a two-component system comprising a resin having a group capable of becoming alkali-soluble by being decomposed upon reacting with an acid, and a photo-acid generator; and a hybrid system comprising a resin having a group capable of becoming alkali-soluble by being decomposed upon reacting with an acid, a low molecular weight dissolution-inhibiting compound having an acid-decomposable group, and a photo-acid generator.
JP-A-5-323590 (the term xe2x80x9cJP-Axe2x80x9d as used herein means an xe2x80x9cunexamined published Japanese patent applicationxe2x80x9d) discloses to use two kinds of photo-acid generators, JP-A-5-181279 discloses to use a photo-acid generator which generates a strong acid and a photo-acid generator which generates a weak acid, and JP-A-11-125907 discloses to use a compound which generates a carboxylic acid having a boiling point of 150xc2x0 C. or higher and a compound which generates acids other than a carboxylic acid.
Further, JP-A-2-19847 discloses a resist composition which is characterized in that the composition contains a resin in which the phenolic hydroxyl group of poly (p-hydroxystyrene) is entirely or partially protected with a tetrahydropyranyl group.
JP-A-4-219757 discloses a resist composition which is characterized in that the composition contains a resin in which from 20 to 70% of the phenolic hydroxyl group of poly(p-hydroxystyrene) is substituted with an acetal group.
Further, JP-A-5-249682 discloses a photoresist composition using a similar resin protected with an acetal group. JP-A-8-123032discloses a photoresist composition using a ternary copolymer containing a group substituted with an acetal group.
Furthermore, JP-A-8-253534 discloses a photoresist composition using a partially crosslinked polymer containing a group substituted with an acetal group.
Although these chemical amplification positive resists can be used effectively as the series capable of ultra minute processing for shorter wavelength light sources, chemical amplification photoresists capable of obtaining excellent resolving power and pattern profiles even when considerable time has elapsed after exposure until post-baking, i.e., having large tolerance of process, are further required. The above-described conventional techniques cannot satisfy sufficiently this requirement.
An object of the present invention is to provide a positive radiation-sensitive composition of a chemical amplification positive resist having large tolerance of process capable of obtaining excellent resolving power and a pattern profile even when considerable time has elapsed after exposure until post-baking.
The above object of the present invention has been achieved by the following means.
(1) A positive radiation-sensitive composition comprising:
(a) a resin whose solubility in an alkali developer increases by the action of an acid;
(b) a compound that generates a carboxylic acid having a molecular weight of 100 or less upon irradiation with an actinic ray or a radiant ray;
(c) a surfactant; and
(d) a solvent.
(2) The positive radiation-sensitive composition as described in the above item (1), which further comprises (bxe2x80x2) a compound that generates a sulfonic acid upon irradiation with an actinic ray or a radiant ray.
(3) The positive radiation-sensitive composition as described in the above item (1), wherein the compound (b) is a compound represented by the following formula (I): 
wherein R11, R12, R13, R14 and R15 each independently represents a hydrogen atom, a straight chain, branched or cyclic alkyl group, a straight chain, branched or cyclic alkoxyl group, a hydroxyl group, a halogen atom, or xe2x80x94Sxe2x80x94R0; R0 represents a straight chain, branched or cyclic alkyl group, or an aryl group; A+ represents S+ or I+; Bxe2x88x92 represents CH3COOxe2x88x92, C2H5COOxe2x88x92 or C3H7COO31; and m represents 2 or 3.
(4) The positive radiation-sensitive composition as described in the above item (1), wherein the resin (a) has an acid-decomposable group represented by the following formula (II): 
wherein R1 represents an alkyl group having from 1 to 4 carbon atoms; W represents an amino group, an ammonium group, a mercapto group, a substituted or unsubstituted aryl group, a substituted or unsubstituted cycloalkyl group, or an organic group containing (i) at least one atom selected from the group consisting of an oxygen atom, a nitrogen atom, a sulfur atom, a phosphorus atom and a silicon atom, and (ii) at least one carbon atom; and n represents a natural number of from 1 to 4.
(5) The positive radiation-sensitive composition as described in the above item (1), wherein the resin (a) is a resin in which phenolic hydroxyl groups in an alkali-soluble resin are at least partly protected with the acid-decomposable group represented by the formula (II).
(6) The positive radiation-sensitive composition as described in the above item (1), which further comprises an organic basic compound.
(7) The positive radiation-sensitive composition as described in the above item (1), wherein the compound (b) is at least one compound selected from the group consisting of the following (PAG-B1) to (PAG-B6): 
(8) The positive radiation-sensitive composition as described in the above item (7), wherein the compound (b) is at least one compound selected from the group consisting of the above (PAG-B1) and (PAG-B4):
(9) The positive radiation-sensitive composition as described in the above item (1), which contains the compound (b) in an amount of from 1 to 20 wt % based on the solid contents.
(10) The positive radiation-sensitive composition as described in the above item (2), wherein the compound (bxe2x80x2) is a compound represented by the following formula (PAG3), (PAG4) or (PAG6): 
wherein Ar1 and Ar2 each independently represents a substituted or unsubstituted aryl group; R203, R204 and R205 each independently represents a substituted or unsubstituted alkyl or aryl group; R206 represents a substituted or unsubstituted alkyl or aryl group; A represents a substituted or unsubstituted alkylene, alkenylene or arylene group.
(11) The positive radiation-sensitive composition as described in the above item (2), which contains the compound (bxe2x80x2) in an amount of from 1 to 20 wt % based on the solid contents.
(12) The positive radiation-sensitive composition as described in the above item (4), wherein W of said formula (II) is a group represented by the following formula: 
wherein R2 represents a hydrogen atom, a straight chain, branched or cyclic alkyl group having from 1 to 6 carbon atoms, a straight chain, branched or cyclic alkenyl group having from 2 to 6 carbon atoms, a substituted or unsubstituted aryl group, or a substituted or unsubstituted aralkyl group; R3 represents a hydrogen atom, a straight chain, branched or cyclic alkyl group having from 1 to 6 carbon atoms, a straight chain, branched or cyclic alkoxyl group having from 1 to 6 carbon atoms, a halogen atom, a nitro group, an amino group, a hydroxyl group, or a cyano group; X represents a halogen atom; R4 represents a substituted or unsubstituted aryl group, or a substituted or unsubstituted cycloalkyl group having from 3 to 15 carbon atoms; m represents a natural number of from 1 to 4.
(13) The positive radiation-sensitive composition as described in the above item (4), wherein the resin (a) is a resin in which 5 to 45 mol % of an entire phenolic hydroxyl groups in an alkali-soluble resin are protected with an acid-decomposable group represented by the formula (II).
(14) The positive radiation-sensitive composition as described in the above item (1), wherein the resin (a) has a weight average molecular weight of from 3,000 to 80,000.
(15) The positive radiation-sensitive composition as described in the above item (1), wherein the surfactant (c) contains at least one of a fluorine atom and a silicon atom.